This invention relates to a powder agitator used for an ionized beam deposition device or an ion implantation device, and more particularly to a powder agitator exhibiting increased powder agitating characteristics.
A conventional ion implantation device is generally constructed in such a manner as shown in FIG. 4. More particularly, it includes a vacuum casing 1, which is kept at a high vacuum due to evacuation by means of a vacuum pump (not shown) connected thereto. The vacuum casing 1 is also connected to an ionization chamber (not shown).
The vacuum casing 1 is provided therein with a vessel 2 and a plurality of propeller blades 3. The vessel 2 is formed of a metal material into a substantially cylindrical shape. The vacuum casing 1 thus constructed cooperates with a drive section 4 arranged outside the casing 1 to provide a powder agitator. The vessel 2 is grounded to discharge positive charges on powders A in the vessel 2. The drive section 4 causes the vessel 2 and propeller blades 3 to be rotated in direction opposite to each other, resulting in the powders A in the vessel 2 being agitated.
The vacuum casing 1 is also provided therein with a neutralizing filament 5 for neutralizing positive charges of ions, so that electrons may be showered in the vacuum casing 1. Further, the vacuum casing 1 is a Faraday cup 6 for measuring the amount of ions implanted, a beam guide 7 for guiding ionized beams, and the like. The vacuum casing 1 is also provided at a portion thereof connected to an ion source with a deflection coil 8 and a shutter 9.
In the conventional ion implantation device constructed as described above, a material to be implanted is ionized in an ionization chamber (not shown) and impinged on the powders A in the vessel 2 while being accelerated at a voltage of 10 to 400kv, resulting in the ions being implanted in the powders. The conventional device causes the implantation to be limited to a depth as small as about 0.1 micron.
Also, the ion implantation requires to eliminate positive charges of the ions by neutralizing or discharging. However, a failure in the neutralization or discharge causes the positive charges to be loaded on the powders A, resulting in a material to be implanted being scattered or dispersed toward a periphery of the vessel.
The conventional powder agitator, as described above, is so constructed that the propeller blades 3 arranged in the vessel 2 agitate the powders A, therefore, it fails in satisfactory agitation of the powders A unless the amount of powders A to be treated is large. However, an increase in amount of the powders A causes a period of time required for ion implantation to be significantly increased.
In addition, the conventional powder agitator includes a rotation section comprising the vessel 2 and propeller blades 3, so that dusts discharged from the drive section adversely affect the rotation section.
Further, the vessel 2 is charged with a large amount of powders A, resulting in rendering uniform distribution of electrons for neutralization throughout the powders A difficult. In particular, when the powders A to be treated have high resistance, it is impossible to neutralize positive charges of ions and discharge the positive charges from the vessel 2, so that the powders A are kept positively charged, resulting in most of a material to be implanted being scattered toward a periphery of the vessel 2.
Moreover, in the conventional powder agitator, it is required to locate the vessel 2 and propeller blades 3 at a relatively high position with high accuracy. Otherwise, there often occurs a trouble that particles of the powders A pass through gaps between the propeller blades 3 and the vessel 2 or are caught therebetween.
The above-described disadvantages of the conventional powder agitator are likewise encountered with an ionized beam deposition device.